What musical instrument did Leonardo da Vinci design with strings played by rotating wheels?

Leonardo da Vinci designed the viola organista, a keyboard instrument whose strings were sounded by rotating wheels.

Leonardo developed sketches for the instrument in the late fifteenth century. It combined features of a keyboard and bowed string instruments: pressing keys selected strings, while friction from rotating wheels caused them to vibrate. The idea aimed to let one performer produce the sustained sound associated with bowed instruments while using a keyboard layout.

Several versions appear in Leonardo’s notebooks, showing that he refined the mechanism rather than producing only one fixed design. The instrument was not successfully established in Renaissance musical practice, and no known surviving original built by Leonardo exists. Modern makers have constructed working versions from the drawings.

The viola organista is not simply a viola with a keyboard. It is also not the same as a conventional organ, because its sound comes from vibrating strings rather than pipes. Its importance lies in Leonardo’s attempt to unite mechanical motion, keyboard control, and bowed-string timbre.